The present invention relates to a method for the pre-estimation of the extruding pressure and extruding velocity in the preparation of an extrusion-molded article of particle-reinforced composites. More particularly, the invention relates to a method for the determination of the extrusion-moldability of particle-reinforced composites without actually undertaking the process of extrusion molding and to a method for the pre-estimation of the extruding pressure and extruding velocity prior to actually undertaking extrusion molding of particle-reinforced composites.
In the process of extrusion molding of particle-reinforced composites, in general, the material under extrusion is under an action that, while being compressed with a shearing force in the extrusion-molding machines, the particle-reinforced composites are squeezed out in a form by passing through the extrusion die mounted on the end of the extrusion-molding machines so that the materials for extrusion molding are required to have a special property as combinations of flowability and shape-retentivity. Accordingly, the property required for the composites to be extrusion-molded is within a limited range as compared with the particle-reinforced composites for the cast-molding methods with sheathing panels or wet-molding methods with screen-filters and the composites are imparted with practical extrusion moldability only when the composites are prepared within a limited range of formulation. Further, it is very important in the preparation of extrusion-molded products to pre-estimate the extruding pressure and extruding velocity without actually undertaking the process of extrusion molding by factory-size machines from the standpoint of accomplishing high productivity and good maintenance of the production plant. Nevertheless, no reliable method has been developed heretofore for the pre-estimation of the extruding pressure and the extruding velocity and no definite guidelines are available therefor. The only way to determine the extrusion moldability of particle-reinforced composites is to repeat the actual process of extrusion molding in a trial-and-error basis to seek the optimum formulation of the component materials to comply with the extruding pressure and extruding velocity required in the running conditions of the extrusion-molding machines such as revolution of the screws therein.
In this way, the extruding pressure and extruding velocity in the conventional process in preparing of extrusion-molded articles of particle-reinforced composites heretofore undertaken cannot be predicted. Namely, test extrusion molding is repeatedly undertaken with the composites to find out a guideline for the modification or optimization of the formulation of the respective component materials to comply with the desired extruding pressure and extruding velocity finally arriving at optimum extruding conditions. Such a trial-and-error procedure naturally takes a great deal of man power and time.